Stringed musical instruments may produce sound by plucking or strumming the attached strings, which may be stretched between the body and the neck of the instrument. The body may be used to amplify and sustain the string vibrations. The neck of the instrument may be used to support the string tension and to allow the user to change the pitch of the string by pressing along the length of the neck's fingerboard to form the different notes. Typically, the neck may not be considered the primary contributing component of the instrument's sound.
Stringed instrument necks may be constructed from materials such as wood or plastic, and may be reinforced with materials such as carbon fiber or metal alloys, to maintain the rigidity required. Neck designs may include a truss rod that may allow the user to adjust the amount the neck deforms or bows. String tension and environmental factors, such as humidity and temperature, may cause the neck to deform or bow.
Prior art necks may have a cross-sectional profile resembling a semi-circle. The fret board may be located on the top portion of the semi-circle and may be where the fingering from the user occurs. The rounded portion of the semi-circle may lie underneath the fret board and may act as a means to support the player's hand. A number of specialized apparatus may be required to fabricate these prior art semi-circular necks. Also, if the neck is constructed of wood, large amounts of material may be wasted due to the shaping required to form the semi-circular pattern. Fabricating these types of necks requires a highly specialized work force that is experienced in detailed wood work.
Prior art necks were generally designed to act as a unitary member within the musical instrument. In such a design, the main structure of the neck and the fingerboard may be fastened together, or may be fabricated from a single piece of material. The end result may be a neck structure that is relatively massive. A large vibration force may be needed to excite the neck enough to produce an audible difference in the overall instrument's sound. Such a large force is typically not achievable from the instrument.
Furthermore, removable or bolt-on necks may have a flat section on the bottom side, referred to as the neck heal. The neck heal may fit into a mating cut-out or pocket in the instrument's body, and may be held in place with some type of fastener. This method of attaching a neck to a body may limit the design alternatives for the body, due to the required attachment geometry. The neck and body mating requirement may require that the instrument have sharp edges in the area of the neck to the body joint. The neck and body mating requirement may further require an overall thickness of the instrument at the neck to the body joint that makes playing the instrument in that area uncomfortable.
One solution to the neck and body mating requirement has been to construct an instrument with a neck that is permanently attached to the body's structure. Examples of permanent neck attachments include a glued-in neck, and a neck-thru design wherein a single central piece of wood extends from the bottom of the body and continues to form the neck structure. Two pieces of wood or other material may be glued to either side of the central piece to form the body's wings. This method may resolve the issue of playing comfort by not requiring the pocket geometry of a bolt on design, but may have other disadvantages. One such disadvantage is the permanent nature of the neck to body joint. It may be difficult to replace the neck without damaging the whole instrument.
When tuning the strings of a musical instrument, a compression force may be applied to the neck that may tend to bow the neck upwardly. The upward bow in the neck may cause the distance between the strings and the fingerboard to increase. The increased distance between the strings and the fingerboard may affect the ease of playing the instrument, because more force is required to push the strings down onto the fingerboard. It also may cause the instrument to play the note out of tune, because the string may be stretched further when the string is pushed down onto the fingerboard.
Prior art necks have alleviated neck bowing by inserting a truss rod into a channel formed down the center of the neck's structure. The truss rod may comprise a rod threaded on one end, whereby tightening of a nut produces a force on the neck that opposes the bowing force of the strings. The truss rod may provide only a downward force to counter the string pull. Other prior art neck designs comprise two rods arranged one on top of the other, whereby shortening the length of one of the rods (by tightening a nut, for example) causes the rod assembly to bend in the direction of the shortest rod. This bending may cause a force opposite to the string force to be applied to the neck.
A disadvantage of the single truss rod and the two rods arranged one on top of the other is the inconsistency of the compression force that is exerted on the neck in the horizontal axis. The inconsistency of the compression force in the horizontal axis may cause the neck to twist. Conventional truss rods may not be able to counter the twisting effect.
A need exists for a stringed musical instrument neck that overcomes the disadvantages of prior art necks.